Agent Communications

Versal ACAP Technical Reference Manual (AM011)

Document ID
AM011
Release Date
2022-04-26
Revision
1.4 English

The communications between the two agents depends on their prearranged protocol. The IPI provides a framework for this communications.

Source Agent Initiates Action

To generate an interrupt, the source agent writes a 1 to a bit in its trigger (TRIG) register that corresponds to the destination agent. The source agent can verify that the bit is set in the destination agent's status register by reading its own observation (OBS) register. However, it cannot determine if the interrupt is enabled to generate the IRQ interrupt signal to the destination processor without accessing its GIC interrupt controller.

Destination Agent Response

When an agent receives an IPI system interrupt, it reads its IPI interrupt status register (ISR) to determine the source agent. After servicing the interrupt, with or without a message response, the destination agent clears its ISR by writing a 1 to the bit. This clearing of the destination ISR bit can be detected by the source using its observation register. The destination agent can also issue an IPI system interrupt back to the source agent.